Open AccessA Longitudinal Evaluation of Thyroid Function in Critically III Surgical Patients
Author(s) -
Gary P. Zaloga,
Bart Chernow,
Robert C. Smallridge,
Russ Zajtchuk,
Kathryn Hall-Boyer,
Ronald W. Hargraves,
C. Raymond Lake,
Kenneth D. Burman
Publication year - 1985
Publication title -
annals of surgery
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.153
H-Index - 309
eISSN - 1528-1140
pISSN - 0003-4932
DOI - 10.1097/00000658-198504000-00010
Subject(s) - medicine , thyroid function , critically ill , thyroid , intensive care medicine
Thyroid hormone alterations (known as the "sick-euthyroid syndrome") are common following major surgery, but the time course for appearance and recovery from these alterations has not previously been longitudinally studied in a large group of surgical patients. The authors prospectively studied 59 patients undergoing major surgery (coronary artery bypass grafting, pneumonectomy, or subtotal colectomy). Compared with preoperative values, the mean serum T4, T3, free T3, and TSH concentrations decreased significantly (p less than 0.05) following surgery. Serum reverse T3 and T3 resin uptake index increased, while free T4 levels remained unchanged. These changes were seen within 6 hours of surgery and normalized by 1 week after surgery. Although the serum TSH response to TRH was normal before and after surgery in 56 of the 59 patients, the maximal TRH-induced increase in serum TSH and the integrated serum TSH response to TRH were suppressed in the early perioperative period. This postoperative TSH suppression correlated with elevated postoperative plasma dopamine concentrations (r = 0.57, p less than 0.05). Three patients with compensated primary hypothyroidism were detected in the study and represent the first documentation of serial thyroid hormone and TSH levels in hypothyroid patients undergoing major surgery. These patients had similar changes in thyroid hormone values compared with euthyroid patients. The serum TSH response to TRH was suppressed into the normal range in two of these patients on the day following surgery. The authors conclude that the sick-euthyroid syndrome occurs within a few hours of major surgery and remits with convalescence. Postoperative decreases in serum TSH may mask the diagnosis of hypothyroidism. Surgical consultants should be aware of these rapid postoperative changes so that thyroid function tests are properly interpreted in patients who have undergone major surgery.